Of all the marriages on display in the patchy “Company’’ by Moonbox Productions, none is more awkward than that between Stephen Sondheim’s brilliant score and George Furth’s clunky, dated script.

Furth’s kaleidoscopic approach to this portrait of a single guy named Bobby and his meddlesome band of friends may have worked when “Company’’ premiered in 1970, but now the two halves of the musical exist in a state of constant tension, like an inadvertent illustration of the show’s message about the difficulty of making connections that last.

Time and again Sondheim’s music and lyrics illuminate character, place (New York), situation, and mood with consummate artistry and crisp immediacy, only to have the show’s momentum stalled by Furth’s wan vignettes and facile dialogue, which runs to the likes of “The problem is you want too little. And that’s the hardest thing in the world to get.’’ A smoothly meshing ensemble could just about make this marriage work, but the skill level is too variable among the Moonbox cast for this “Company’’ to develop a consistent dramatic rhythm.

Directed by Allison Olivia Choat and choreographed by Rachel Bertone, with music director Dan Rodriguez leading a nine-member band on Dale Conklin’s bare-bones set, the Moonbox production features a rousing performance of the title song and a few other sparkling moments, including Leigh Barrett’s killer rendition of “The Ladies Who Lunch.’’ However, the air simply goes out of this “Company’’ whenever the music stops.

Ah, but what music. When “Company’’ premiered on Broadway after a tryout in Boston, it kicked off an astonishing decade for Sondheim that would include “Follies’’ (1971), “A Little Night Music’’ (1973), “Pacific Overtures’’ (1976), and “Sweeney Todd’’ (1979), not to mention “Merrily We Roll Along’’ (1981), a box-office flop with a book by Furth that features a gem of a score. That decade represented the fullest flowering of Sondheim’s genius as a composer, one of those compressed bursts of creative achievement — think Lennon and McCartney or Bob Dylan in the 1960s, or Bruce Springsteen from the mid-1970s to the mid-’80s — that can help define an artist’s career, whatever they do before or after. Frequently, there was a decided mismatch between Sondheim and his librettists.

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At the center of “Company’’ is Bobby, who is turning 35 under pressure to settle down from some of his married friends and from his own nagging sense that he’s missing out on something big. Bobby is played at Moonbox by David Carney, who does not yet have a firm fix on the character. Bobby’s surface bonhomie comes through in Carney’s portrayal, but not his lonely-in-a-crowd quality or the essential apartness that helps explain why Bobby can’t commit to a relationship.

Carney does a fairly effective job with the song that spells out Bobby’s tightly circumscribed notion of what a relationship should be — “Marry Me a Little’’ — but the actor’s performance is tentative in two other crucial numbers: “Someone Is Waiting,’’ which should touch the depths of Bobby’s yearning but doesn’t, and “Being Alive,’’ the finale, which should signal his hard-won resolve but registers as a generic anthem instead.

There are a few other signs of growing pains for Moonbox, which launched several years ago and is taking a laudably ambitious step by tackling “Company’’ and by performing in the Roberts Studio Theatre rather than the smaller theater it has previously called home. On opening night, the production was marred by a few sound glitches, resulting in periodic squawks and a couple of audibility issues.

Shonna Cirone is amusing and touching as Amy, a bride-to-be coming apart at the seams as she experiences an epic case of pre-wedding jitters. But the tempo is too slow on Cirone’s big number, “Getting Married Today,’’ whose words should burst from Amy at an auctioneer’s pace. Cast standouts include Brockton native Matthew Zahnzinger as Harry and Katie Clark as April, a stewardess whom Bobby is dating. Recently seen as Morgan Le Fey in New Repertory Theatre’s “Camelot,’’ Clark brings a poignant edge of self-awareness to April, a character sometimes played solely as a ditz. Clark also joins Lisa Dempsey and Megan Alicia in a snappy version of “You Could Drive a Person Crazy,’’ a comic diatribe about Bobby from the women he’s strung along.

But it is Barrett, predictably, whom you’re likely to remember best from this “Company.’’ Playing Joanne, the jaded socialite made immortal by Elaine Stritch, Barrett takes an emotional journey in “The Ladies Who Lunch’’ that travels in the space of a few minutes from confident mockery to a kind of self-recognition mixed with equal parts disgust and defiance. It’s a small master class in how not just to sing but to act a song. Moonbox cast, watch this woman closely.

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